Abstract: A method and apparatus for managing the flow of data within a switching device is provided. The switching device includes network interface cards connected to a common backplane. Each interface card is configured to support the maximum transfer rate of the backplane by maintaining a “pending” queue to track data that has been received but for which the appropriate routing destination has not yet been determined. The switching device includes a switch controller that maintains a central card/port-to-address table. When an interface card receives data with a destination address that is not known to the interface card, the interface card performs a direct memory access over a bus that is separate from the backplane to read routing data directly from the central table in the switch controller.

Abstract: In a data network, a source node transmits a data packet to a destination node across interconnected switches whereby a switch, upon receiving the data packet from the source node, queries other switches in the network for the appropriate switch and port on the switch out which to forward the data packet to the destination node. The appropriate switch responds to the query with its switch number and the port number of the port out which the data packet should be sent to reach the destination node. The querying switch caches the switch number and port number and prepends a destination tag to subsequent data packets it receives which are destined to the same destination node, thereby providing a distributed system among the switches in the network for maintaining detailed information regarding the appropriate switch and port out which to forward data packets received by a source node in the network.

Abstract: A method and apparatus for a node being inserted into a token ring local area network to sense the data transmission speed of the token ring LAN and automatically setting the data transmission speed of the node to match the data transmission speed of the token ring LAN. The token ring LAN may operate at either 4 megabits per second or 16 megabits per second. The node recovers data transmitted on the token ring, and determines, based thereon, the speed of the data transmission and configures the speed at which the node transmits and receives data to/from the token ring network accordingly.

Abstract: The switch fabric of the ATM switch, i.e., the ATM switch backplane bus, switches a cell based on routing information provided by the source LAN or ATM module to an output port on a destination LAN or ATM module of the switching hub. In the described system, the ATM switch is preconfigured to provide a fully connected topology between ports of all modules. In one embodiment, ATM cells transmitted across the ATM switch fabric between a source LAN or ATM module and a destination LAN module, e.g., Token Ring, FDDI or Ethernet, is accomplished by way of a routing tag prepended on the ATM cells. The routing tag provides both unicast and multicast group destination information such that the ATM cells are routed to the appropriate port on a given destination module without the need to establish a virtual circuit between the source module and the destination module using VPI/VCIs.

Abstract: In a segmentation and reassembly module in a local area network switch module, a method and apparatus for storing fixed length data cells received from an ATM network in a plurality of memory buffers during the reassembly of the data cells in to a variable length data packet to be transmitted on an attached local area network.

Abstract: A token ring network having virtual token rings comprised of one or more physical token rings. A media access control (MAC) layer device such as a bridge or switching hub has at least two ports assigned the same ring number such that token ring segments connected to the ports operate as though on the same physical token ring segment even though they are electrically isolated. All physical rings in the same virtual ring are considered to be in the same broadcast domain.

Abstract: A method and apparatus for filtering data packets from a network device, such as a LAN switch, onto a network coupled thereto based on the content of the data packets. A pattern is defined and a forwarding action performed on data packets whose contents match or do not match the pattern, according to a specified condition. Filters may be configured on a per port basis, i.e., a filter can be applied to data packets entering or exiting a specific port on a networking device such as a LAN switch. A data packet received or transmitted at a port of a network device whose contents meet a condition specified by a filter may be processed in a number of ways: the packet may be forwarded to a normal destination port according to normal forwarding rules, forwarded to additional destination ports, forwarded to a monitor destination port, dropped, or subjected to another filter. The next filter may define a different forwarding action for data packets that do not meet the condition specified by the present filter.

Abstract: Methods and apparatus providing for a switching hub in which an asynchronous transfer mode (ATM) switch is utilized as a backplane bus to which a plurality of LAN and ATM modules are coupled. Each LAN or ATM module is an autonomous switching module. Thus, for example, an Ethernet LAN module may receive Ethernet packets on one of its ports and transmit the packets out another one of its ports according to well known standards and techniques for bridging such packets, without the need for such packets to be translated into ATM cells and transmitted across the ATM switch backplane bus.

Abstract: A method and apparatus for controlling data flow within a switching device are provided. The switching device includes a cell-switched backplane. Both packet switched and cell switched network interface cards may be coupled to the cell-switched backplane. A destination tag is created for each unique destination port and for each unique set of destination ports. The destination tags are used to index a master destination tag table. The entry of the master destination tag table that corresponds to a given destination tag includes a destination mask that indicates which ports are destination ports the given destination tag. Local tables are built and maintained within each network interface card based on the information contained in the master destination tag table. When a network interface receives data from an external device, the network interface determines the destination tag associated with the data.